The purpose of this program project grant is to continue to develop a clinical program in marrow transplantation. The proposal is made up of 3 projects: (1) Therapeutic application of bone marrow transplantation in malignancy and bone marrow failure; (2) Immunogenetics as applied to clinical bone marrow transplantation; and (3) Immunologic evaluation of patients following bone marrow transplantation. The objectives of the first project are to explore the therapeutic potential of cytoreductive treatment combined with allogeneic, syngeneic or autologous marrow transplantation in human malignancy and in aplastic anemia. The objectives of the second project are to determine the serologic (HL-A) and non-serologic (MLC) identity of marrow graft recipients and donors; establish and MLR identity of marrow graft recipients and donors; establish an MLR typing cell panel; identify non-HLA loci contributing to the mixed lymphocyte response; characterize non-HL-A antisera and the genetic inheritance of antigens recognized, and expand the repertoire of genetically determined hematopoietic markers needed to follow marrow engraftment. The objective of the third project is a comprehensive, in-depth evaluation of the acquired combined immunodeficiency (CID) that occurs after transplantation. Comparisons are to be made between the kinetics of recovery of recipients of allogeneic syngeneic and autologous bone marrow grafts. BIBLIOGRAPHIC REFERENCES: Tutschka, P.J., Schwertfeger, R., Slavin, R.E. and Santos, G.W. Mechanism of Tolerance in Long Term Rat Bone Marrow Chimeras. Exp. Hemat., 1977, in press. Klein, D.L., Bateman, J.L., Sepelak, S.B., Tutschka, P.J., Elfenbein, G.J. and Santos, G.W. In Vivo and In Vitro Measurement of Sensitization to Rat Marrow Allografts. Trans. Proc., 1977, in press.